In recent years, as information becomes more digitized, information is increasingly stored as digitized data. Accordingly, storage devices tend to store ever more vast amounts of data for a long period of time. In those storage devices, data is commonly stored on a recording medium such as a hard disk, a DVD, or a magnetic tape.
Any storage device has a finite life span. In addition, there are cases where higher performance (in terms of access speed, storage capacity, or the like) is required of a storage device. Migration (copying) of data stored on a storage device to another storage device is performed for these reasons.
In this data migration, it is desirable to verify whether or not the migration of data to another storage device (destination) has been performed properly. The time required for the data migration is shorter the better.
As a data migration method according to the related art which verifies whether or not data migration has been performed properly, a method exists which copies data to a destination, then reads data from each of the storage device (source) from which the copied data is read and the destination, and compares both the data. This method makes it possible to reliably verify whether or not data has been copied properly. However, if there are vast amounts of data, it takes a long time to read data from each of the source and the destination and compare both the data. Thus, the time required for data migration tends to become very long.
In another data migration method according to the related art, a predetermined length of data is read from the source, and the area required for writing the read data to the destination is checked. In the other data migration method according to the related art mentioned above, by reading and writing data in predetermined data length units, whether or not the sizes of the read data and the written data match is verified during data migration. Therefore, data migration can be done in a shorter time. However, it is not possible to reliably verify whether or not data migration has been performed properly. This is because the same data size does not guarantee that the contents of both the data are the same.
In data migration, cases need to be considered where data at the source becomes inaccessible for reasons such as that the source storage device is discarded. With this taken into consideration, it can be said that it is important to allow data migration to be done in a shorter time while reliably verifying whether or not the data migration has been performed properly.
Japanese Laid-open Patent Publication No. 2005-242696, Japanese Laid-open Patent Publication No. 2008-117253, and Japanese Laid-open Patent Publication No. 2006-235698 are examples of related art.